Worked materials of metal wire such as tungsten wire and Nichrome wire, machined materials of carbon such as isotropic carbon material and glassy carbon, and metal compounds such as silicon carbide have heretofore been used, principally, as heating element resistances. Of these substances, the worked material of metal wire has been mainly used as a heating element for heaters in a small sized commercial apparatus, and the carbon and metal compounds have been used for industrial furnaces, etc.
Of conventional materials for heating elements, carbon differs from metal wire, etc. in that it is excellent in properties such as a heating rate, heating efficiency and the efficiency of generating far infrared rays. However, because conventional carbon heating elements are produced from large plate-like or block-like bodies by machining, the production process is complicated and costly, and production of thin rods and sheets is difficult. Moreover, the heating elements have a problem in that there are no measures other than to vary the shape of the elements to control the calorific values of the elements because the heating elements are prepared by cutting blocks, etc., having specific resistances in a certain specified ranges.
The present invention has been achieved in view of such problems. An object of the present invention is to provide a carbon heating element the heating of which can be controlled by applying a predetermined current and a predetermined potential in broad ranges because the heating element can be made not only in a sheet-like form but also in a thin rod-like form and a thin cylindrical form that cannot be obtained when the heating element is made of a conventional carbon material and because the heating element can be made to have an arbitrary specific resistance, an excellent heating rate, an excellent-heating efficiency and excellent efficiency in generating far infrared rays, and a method of producing the same.